Plaster roll-out



Sept. 1, 1964 E. L. WALTERS 3,146,563

PLASTER ROLL-OUT Filed Aug- 20, 1962 4 Sheets-Sheet l INVENTOR.

2066c fidlfdpe ATTORNEYS Sept. 1, 1964 E. L. WALTERS 3,146,563

PLASTER ROLL-OUT Filed Aug. 20, 1962 4 Sheets-Sheet 2 INVENTOR. 16 fimmaz ZUaZfWL ATTORNEYS Sept. 1, 19-64 E. L. WALTERS 3,146,563

PLASTER ROLL-OUT Filed Aug. 20, 1962 4 Sheets-Sheet 3 A TTORN E "SUnited States Patent 3,146,563 PLASTER ROLL-OUT Emmett L. Walters,Toledo, Ghio, assignor to Libbey- Gwens-Ford Glass Company, Toledo,Ohio, a corporation of Ghio Filed Aug. 20, 1962, Ser. No. 217,968 12Claims. ((Il. l277) The present invention relates broadly to thesurfacing of glass sheets or plates by the so-called continuous grindingand polishing system. More particularly, the invention is concerned withan improved apparatus for mounting the sheets or plates upon the workcars or tables of such a system.

The primary object of this invention resides in the pro vision of animproved roll-out apparatus for embedding glass sheets in a layer ofplaster of Paris, or other cement used, in such a manner that the glasssheets are secured to the work tables in an efficient and practicalmanner to facilitate the succeeding treatment of the sheets.

Another object of the invention is to provide roll-out apparatus of theabove character including a support frame and a plurality of pressingelements and in which the pressing elements resiliently force the glasssheets downwardly into the laying plaster with substantially uniformpressure to effect the embedding of the sheets on the work tables evenlyand uniformly throughout their entire areas.

Another object of the invention is to provide a roll-out apparatus ofthe above character including novel means for adjusting the amount ofpressure that the pressing elements are caused to exert upon the glasssheets.

Another object of the invention is to provide a roll-out apparatus ofthe above character in which the pressing elements are arranged in axialspaced relation to one another and means is provided for continuouslyremoving accumulations of plaster from the elements thereby obtainingcleaner operating conditions.

A further object of the invention is to provide a rotatable pressingelement of glass sheet roll-out apparatus, said element being adapted torotate about an adjustably mounted axial member and to be movablerelative thereto, in common with like elements of the plurality ofpressing elements, to rapidly adjust the working pressure of the saidelements in a novel, simple and convenient manner.

Other objects and advantages of the invention will become more apparentduring the course of the following description when read in connectionwith the accompanying drawings.

In the drawings, wherein like numerals are employed to designate likeparts throughout the same:

FIG. 1 is a plan view of a roll-out apparatus for glass sheets asconstructed in accordance with the invention;

FIG. 2 is a longitudinal vertical sectional view of the apparatus takenon line 22 of FIG. 1;

FIG. 3 is a detail sectional view of the pressing elements of theapparatus;

FIG. 4 is a transverse, vertical sectional view taken on line 44 of FIG.3;

FIG. 5 is a horizontal sectional view taken on line 5-5 of FIG. 4;

FIG. 6 is a perspective view of a component part of the pressingelements;

FIG. 7 is an enlarged detail view;

FIG. 8 is a transverse, vertical sectional view taken on line 88 of FIG.3;

FIG. 9 is a horizontal sectional view taken on line 99 of FIG. 8; and

P16. 10 is a diagrammatic view of a control system.

It will be readily understood by those versed in the art that, in theso-called continuous system of grinding and 3,145,563 Fatented Sept. 1,1964 polishing glass, a plurality of glass sheets or plates are mountedupon a series of work tables which are arranged end-to-end and movablecontinuously in a substantially horizontal path to carry the glasssheets first beneath and in engagement with the tools of a series ofgrinding units. The partially surfaced sheets are then carried forwardlybeneath the tools or runners of a series of polishing units. While thegrinding and polishing phases of a continuous glass surfacing systemmay, and usually do, follow in regular order, it will be alsoappreciated that glass sheets or plates previously ground on each oftheir surfaces can be brought to the desired final surface and opticalfinish in continuous systems wherein only the polishing operation isexercised. In any event, it is customary to secure the glass sheets tothe tops or decks of the work tables by embedding them within or on arelatively thin layer of plaster of Paris or some other suitablecementing material. This is, of course, achieved by distributing a thinlayer of wet plaster to the decks of the tables, placing a glass sheetor plate thereupon and, before the plaster sets up or hardens, applyingsubstantially uniform pressure over the entire area of the glass sheetto force the same downwardly into the plaster while simultaneouslypressing air and surplus plaster from between the glass and the table.The quality of the resultant finish on the glass and the amount of lossby breakage during the grinding and polishing operations is thereforelargely dependent upon the proper and level securement of the glasssheets to the supporting work tables.

Referring now particularly to FIGS. 1 and 2 of the drawings, there isshown a roll-out apparatus constructed in accordance with the presentinvention and designated in its entirety by the numeral 15. As hereinillustrated the apparatus 15 is conventionally located in superimposedrelation to a series of work tables 16 which are continuously movedforwardly to carry glass sheets 17 therebeneath in the well-knownmanner. Preparatory to engagement of the glass sheets by the apparatus,the well-cleaned decks of the tables 15 are covered with a layer 13 ofplaster of Paris and the sheets or plates are lightly laid thereon insuccessive, end-to-end relation. Thus, as the tables are moved forwardlythe glass sheets in succession are engaged by the pressing elements,generally designated by the numeral 19, of the roll-out apparatus 15,which are adapted to engage the entire area of each sheet and therebypress the same evenly and uniformly into its secured relation in theplaster layer 18.

Generally speaking, the apparatus 15 includes a substantiallyrectangular frame 25 formed with side structural channel members 26 and2'7 and transversely disposed structural members 28 securedtherebetween. The frame 25 is herein, although not necessarily, providedwith a mobile type of support as by the pairs of wheels 29 and 3-0. Thepair of wheels 29 are supported by suitable axles journaled in bearings31 mounted on the channels 26 and 27 while the pair of wheels 30,connected to the opposite ends of jack shafting 33, are likewisejournaled in bearings 31.

The pairs of wheels 29 and 30 are adapted to be supported on tracks 34arranged along and parallel to the path of movement of the tables 16.The shafting 33 is connected through chain drive 35 to a source of power36 whereby the pair of wheels iii? are power driven and the pair ofwheels 29 through the sprocket chains 37; the chains 37 being entrainedabout sprockets 38 attached to the wheels 29 and 30. During operation ofthe source of power 36, the apparatus can be propelled forward and backover the sheets to be uniformly embedded in the layer of plaster. Sincethe novel aspects of the present invention reside essentially in thepressing elements 19 and the structures thereof, the frame 25 canalternatively remain stationary or can be mounted on pedestals fixedlyinstalled on opposed sides of the series of work tables.

As viewed in FIG. 1, the pressing elements 19 are arranged tandem-wisein three axially parallel rows in the frame and each consists of aplurality of rollers arranged in regularly spaced relation to oneanother. As herein disclosed, the rollers of the first and third or lastrows are aligned with one another to traverse identical paths across theglass sheets or plates moving therebeneath while the rollers 4d of thesecond or intermediate row are arranged in offset or staggered relationto overlap the paths of pressure of the rollers of the leading orfollowing rows. This provides substantially complete, equallydistributed pressure over the entire area of the glass sheets or platesand thus acts to embed the same in a plaster layer of uniform thickness.

Since the elevation at which the frame 25 is located and/or supportedabove the deck or top surface of the work tables 16 is nominally fixedat a predetermined height, the working pressure of the rollers 40 isestablished initially by the actual positioning of the pressing elements19 in relation to the tables surface. This positioning or the height ofthe rollers peripheral surface is, of course, obtained by the combinedthicknesses of the plaster layer and of the glass sheets to be surfaced.One of the novel aspects of this invention is to provide means for thenestablishing, and modifying when necessary, the specific degree ofpressure with which the rollers 49 engages the glass sheets and pressthe same in the plaster layer thereby securing the sheets in uniformlylevel relation to the tables. Additionally, means is herein provided forcontinuously breaking up and preventing the accumulation of plasterwhich would otherwise adhere to the edges of rollers in the spacestherebetween and create objectionable interference to the otherwisesatisfactory operation of the individual roller and its cooperativeutility with adjoining rollers.

For these purposes, the rollers 49 of each of the pressing elements 19are generally supported on a tubular or hollow arbor 41 of square crosssection which is carried at its opposite ends by arms 42. As shown inFIG. 2, one end of each arm 42 is pivotally mounted by a pintle pin 43in bracket 44 on an adjoining transversely disposed channel 28 of theframe 25. The opposite or free end of each arm 42 is adapted to restupon an adjusting screw 45 supported in a structural plate 46 of theframe 25 and equipped with lock nuts 47. Vertical adjustments of thescrews 45 at the respective ends of each pressing element obtains theinitial positioning of the rollers relative to the work tables. Tobodily raise each of the pressing elements, the free end of each arm 42is attached by clevis 48 to the piston rod 49 of a cylinder 50. As shownin FIGS. 1 and 2, the cylinders 50 are mounted on structural plates 51of the frame and through piping 52 are connected to a suitable source ofpressure (FIG. 10). Accordingly, the initial positioning of the pressingelements 19 is obtained by the adjusted height of the screws 45 whilecomplete removal or raising of the elements from the surface of theglass sheets is effected by the application of pressure to the severalhydraulic cylinders 50.

With more particular reference to the structure of the pressing elements19, it will be seen in FIGS. 3 to 7 inclusive that each consists of aplurality of rollers 4-0 and end retaining members, generally designatedby the numeral 55. Each roller 40 is formed by a peripheral rubber rollor tread 56 adapted to be freely rotatable on a supporting core member57. To provide a wear-resistant outer surface and more resilient innerbody portion, each tread 56 includes an outer rubber layer 58 having ahardness of approximately 35 to 40 Shore A durometer with the inner bodyportion 59 being of 15 to 20 Shore A durometer. In fabricating the tread56, the body portion 59 is vulcanized to a mounting collar 60 havingL-shaped flanged collars 61 secured to the marginal edges thereof. EachL-shaped collar defines an annular recess 62 between the rim 63 of thecollar and the surface of the ring 60 (FIG. 7). Alternatively the treads56 can be circularly recessed to receive the collars 61 and suitablyadhered by cement to the outer surface of the collar 69. The innersurface of the collar 69 is recessed in each marginal edge portion toreceive a bearing member 64, such as a socalled needle hearing, by whichthe ring is rotatably mounted on the core member 57. As viewed in FIG.6, each core member 57 is formed with a central web or wall 65 boundedby an annular rim 66. As herein provided, the rim 66 is equipped with ahardened and ground sleeve 67.

The bearings 64 are maintained from endwise movement and in rollingcontact with the surface of the sleeve 67 by means of ring plates 63which are positioned against the casings of the bearings by means ofsnap-type locking rings 69; said rings being received in grooves 70provided in the inner surface of the collar 60 for such purpose (FIG.7). The core member is adapted to be mounted on the arbor 4-1 forreciprocal motion and also swinging motion within a slight degree ofinclination. For this purpose, the wall 65 is axially formed with anoblong opening 7% having a substantially horizontal dimension finishedso that the vertical surfaces '71 interfit with the vertical wallsurfaces of the arbor, and a vertical dimension between the bottomsurface 72 and top surface 73 is slightly greater than the outerdimension or thickness of the arbor, see FIG. 47 Additionally, the topsurface 73 of opening 79 is notched or upwardly recessed as at '74 forpurposes to be hereinafter more fully described. Integral flanges '75project outwardly from the web 65 with the inher surfaces thereof beingcoplanular with the surfaces '71 of opening 76 Each flange 75 isprovided with an arcuately shaped end surface '7", with the distancebetween the associated surfaces 76 being substantially equal to thewidth of the tread 55 plus the width of the spacing to be maintainedbetween adjoining rollers 40.

As seen in FIGS. 3 and 5, the rollers 40 of each row of pressingelements are thus maintained in spaced relation by the surface tosurface contacting arrangement of the arcuate end surfaces '76 of therespective core members. This positioning of the arcuate surfaces 76also permits free cooperative or individual rocking action therebetweenand as occasioned by one or more of the rollers due to the presence offoreign particles, such as lumps of plaster, on the surface of a glasssheet without similar rocking action being necessarily experience by anadjoining roller. The end retaining members 55 are arranged at theopposite ends of each row of pressing elements 19 and are adapted toengage the surfaces 76 of the endmost flanges 75 thereby maintaining therollers 40 in the above described cooperative relationship. And thespace between each of the rollers 46 is closed by a flexible ring ordiaphragm member 8i).

As shown in enlarged detail in FIGS. 3 and 7, the flexible ring ordiaphragm member 30 is located between each of the adjoining rollers 40and disposed inwardly from the outer active surfaces thereof to thusdefine a boundary surface of the spaces between the rollers.Essentially, the ring or diaphragm members function in two capacities,while serving to substantially close the defined spacing, in that theyresiliently accommodate angular, or other, displacement of one rollerrelative to another while maintaining an effective tight sealtherebetween. More especially, the diaphragm members are formed of arubber material and are adapted to rotate with the treads S6 and to becontinuously deformed in an outwardly directed action to break upaccumulations of plaster from between the opposed end surfaces ofadjoining rollers.

The members 80 are circular in outline and in cross section generallyresemble a modified capital letter M in that they are produced with aconcave or V-shaped center wall portion 31 and two inwardly directedflanged walls 82. Outwardly of the flanged walls 02 there are formedwedgeshaped marginal edge portions 83. Preparatory to the assembly of adiaphragm member in cooperative relation between two adjoining rollers40, L- shaped retainer rings 34 are adhered to the outer surfaces of theflanges 82 at the inner marginal edge thereof around the circular wall85 and with the flange or rim 05 projecting outwardly. The wedge-shapededge portions 83 are then inserted into the recesses 62 with the outersurfaces thereof closely interfitting with the annular rim 63 of therespective collars 61. This positions the rim 86 of the retainer ring 84in supported relation on the outer margin of the mounting collar 60. Inthis relationship, the wedge-shaped ends 83 and the rims 86 enclose therecess 62 to convert the same into a more or less sealed chamber whichmay be filled with a lubricant such as a silicone grease or likesuitable material.

In use, the sectors 88 and 09 of the concave center wall 81 are adaptedto be distorted or distended outwardly, as shown in FIGS. 4 and 5, thusoperating to continuously prevent the drying of plaster in the spacebetween the rollers and causing outward movement of the material ontothe glass surface from which it is customarily removed by water spraysand brushing. This distending action is carried out in one area of thewall 81, as indicated by the reference letter A in FIG. 4, by aball-bearing, or permanently lubricated bushing wheel 90. The wheel isjournaled on a screw 91 threaded into the outer end of a bracket 92mounted by screws 93 on a flanged portion 75 of the core member 57 ofeach roller 4-0. As best seen in FIGS. 4 and 5 and during rotation ofthe plurality of rollers, the inverted wall 81 of each diaphragm member80 is deflected outwardly while moving in contact with the wheel 90 andthen by its inherent elastic characteristic returns to the normalinverted or concave relation of the wall portions 83 and 09 which arethus swung outwardly and inwardly from the central crotch area 94 to thejuncture of each portion 88 or 89 with the integral flanged walls 82.

As viewed in FIGS. 3 and 5, each of the end retaining members 55includes means for engaging the arcuate surface 76 of the endmostflanges 75 as well as for sealing the endmost roller per se from theentry of foreign matter in substantially the same manner as theabovedescribed diaphragm members 80. For this purpose, a retention bar100 is mounted on the vertical walls of the arbor 41 by means of screws101 which are passed through notches or slots 102 in the bar 100 (seeFIG. 9). This permits endwise adjustments to be made between thecontacting surfaces 76 of the plurality of rollers 40 before the bars100 at the opposite ends of the arbor are secured in like contactingrelation to the endmost flange surfaces.

The outer surface of each endmost roller is also substantially sealed bythe provision of wear rings 103 and 104 having suitably finishedsurfaces that are resiliently maintained in contact with one another;the ring 103 revolving with the roller while the ring 104 is maintainedstationary with regard to the arbor 41. Thus, the peripheral edge of therelated collar 60 is provided with substantially equally spaced tappedholes for receiving screws 105 by which a spacing ring 106 and the wearring 103 are mounted to said collar. The ring 104, on the other hand, issupported by screws 107 on an annular plate 108 carried by the arbor 41and provided with a substantially rectangular opening 108 through whichthe arbor is received. As viewed in FIGS. 3 and 8, the upper and lowersurfaces of the opening are finished with arcuate surfaces 109 in orderthat the plate 108 can rock through a vertical plane in response to anyrocking movement of the adjoining roller 40. This is, of course,transmitted to the said plate by the interaction of the rings 103 and104 as the ring 103 is. deflected from the vertical plane with theroller 40 and the ring 104 angularly moves in agreement therewith. Thering 104 is adapted to be supported in surface bearing contact with thering 103 by the plate 108 which is resiliently urged by a pair of coilsprings 110, one end of which are received in sockets 111 provided inthe oppositely disposed surface of the plate (FIG. 9). The opposite endsof the springs are similarly received in sockets 112 provided in anannular plate 113 fixed on the arbor 41 by screws 114. The springs arediametrically aligned in a substantially horizontal plane through theaxis of the arbor 41. Consequently, during any rocking motion of theplate 108 as influenced by deflection of the associated roller 40 and astransmitted through the surface to surface relationship of the rings 103and 104, the plate 108 will swing slightly on the arcuately formed edgesurfaces 109 of the opening while urging the ring 104 against ring 103by the action of the springs 110. As aforementioned, the rollers 40 areadapted to rise and fall with reference to the arbor 41, and in theinstances of these endmost rollers 40 equipped with wear rings 103, thesaid rings will easily slide vertically while being maintained inbearing contact with ring 104.

To substantially house and enclose the rings 103 and 104 and the plates108 and 113 and more particularly the adjoining ends of the endmostrollers 40, a flexible sleeve 115 is placed thereover. The sleeve 115 isformed with a hollow and square hub 115 for receiving the arbor 41; asubstantially fiat wall 117 and tubular wall 13 including a corrugatedor bellows-like portion 119. The free end of the tubular wall 110 isshaped to interfit with and be located on the annular edge of the plate100 and outwardly is formed with an L-shaped flange 120 located in closeproximity to and having a rim 121 disposed in spaced slightlyoverhanging relation to the adjacent annular edge of the ring 103. Sincethe ring 104 follows slight angular deflections of the ring 103, anytemporary deformation of the tubular wall 118 will be absorbed in thebellows 119. Likewise in the event the roller 40 with the ring 103 isadjusted vertically relative to the arbor 41, the spaced relationbetween the ring and the rim 121 of flange 120 will accommodate suchmovement.

During positioning of the pressing elements 19 for most effective actionupon the glass sheets to embed the same evenly and uniformly over theirentire area in the plaster layer 10, each element 19 is initiallylocated through the arms 42 and by adjustment of the screws 45 toproduce a desired amount of pressure as, for example, a maximum workingpressure of 75 lbs. This pressure is then, or eventually, modified byvertical dispdacement of the rollers 40 relative to their respectivearbors 41. For this purpose, the arbors are sealed at their ends byplates 125 to create pressure chambers therein and at equally spacedpoints substantially centrally between the edges of the core members 57,the upper Wall of the arbor is provided with drilled and tapped passages126 to receive pressure responsive expandable bellows members 127. Thebellows 126 are equipped with threaded ends 120 by which they arelocated in the respective tapped openings. The bellows are thus locatedin the aforementioned notches 74 of the opening 70 of each core member.Now upon the application of a pressure medium, such as air underpressure, the several bellows will be distended, and, acting against theupper surface of the associated notch, raise the core member and, moreespecially, the rollers 40 relative to the arbor. In so doing, the coremember 57 is slidably moved within the limits of the longer verticaldimension of the oblong opening 70 with the wall surfaces 71 movingrelative to the vertical wall surfaces of the arbor.

In order to supply the pressure chamber within the arbor from aconvenient source of control, a fitting 120 is attached to a wall of thearbor as in FIG. 5 and connected by piping 130 (FIG. 10) extended to asource of power, such as the pump 131, through the valve 132.Additionally, the arbor 41, adjacent its ends is provided with auxiliaryconduits 133 (FIGS. 3 and 5) connecting the bellows 127, associated withthe endmost rollers, designated by the numeral 134 of the first and lastrows of pressing elements, with individual source of pressure such as atthe fitting 135 located in tapped opening 136. The conduits 133 areformed by pieces of tubing bent U-shape and with the upwardly directedends 137 thereof passed through the respective tapped openings 126 and136 and placed in sealed relation as the bellows and/ or fitting isturned inwardly thereagainst. The reason for this separation of pressurecontrol for the endmost rollers 134 is to provide a differential in theamount of pressure exerted along the marginal edges of the glass sheetsor plates while maintaining a uniform amount and distribution ofpressure over the remainder of the sheets and for all practical purposesthe entire area thereof.

In actual practice in continuous systems for grinding and polishing thesurfaces of glass sheets or plates, a series of work tables 16 areconveyed in a substantially endless horizontal path with the activecycle originating at an area wherein the top surfaces or decks of thetables are thoroughly cleaned and covered by a thin layer of wet plasteror like cementing material. Rough or partially finished glass sheets orplates 17 are then laid on and embedded in the plaster layer and, as theplaster sets up and hardens, are firmly adhered to the work table. Inorder to insure that the sheets or plates are uniformly level throughoutthe entire area of their surface, roll-out apparatus of the type hereindisclosed is employed to press upon the upper surfaces of the sheetsthereby locating the said surfaces at a substantially common height fromthe surface of the table, to obtain a uniform thickness of finishedsheets and also to expel air and surplus plaster from beneath the glass.Accordingly, in positioning a roll-out apparatus above and across thepath of movement of the work tables, an initial elevation of thepressing elements 19 is obtained by adjustment of the screws on whichthe free ends of arms 42 are supported. This determines the height ofthe rollers 40 and arbor 41 of each pressing element 19 above the deckof the work table or to produce the predetermined amount of pressure tobe exerted on the surfaces of the glass sheets passed therebeneath. Nowthrough the use of valves 132, a pressure medium, such as air, isdirected from the pump 131 through piping 139 to each of the hollowarbors 411 to effect elongation of the plurality of associated bellowsmembers $.27 thereby raising the rollers 40 relative to the respectivearbor and thus modifying the amount of rolling pressure exerted on thesheets. In order that the amount of pressure applied along the oppositemargins of the sheets can be varied from that applied over the remainderof the entire area, the valves 138 are employed to introduce airpressure through piping 139 into the conduits 133 and to the bellowsassociated with the endmost rollers designated by the numeral 134.

During such vertical adjustments of the rollers 40 and/or 134-, the sameare guided upwardly or downwardly by the sliding relation of thesurfaces 71 of each core member 57 with the vertical wall surfaces ofthe arbor 41 while the tread is freely rotating relative to said coremember on the bearings 64. These bearings are protected against theentry of dirt, Water and more especially wet plaster by the diaphragmmembers arranged between each of the rollers and also by the sleeves ofthe retaining members 55 associated with the endmost rollers 134. Asplaster accumulates between the rollers, the wheels 99 operate toprogressively distort the wall 81 of the diaphragm members 89 to breakup the plaster and force the same outwardly onto the glass surface fromwhich it is washed. Since an adjacent diaphragm member 80 as well as thesleeve 115 associated with each retaining member 55 constitute flexiblesealing means, the endrnost rollers 1 4- may be vertically displacedrelative to the arbor and adjoining roller 40 and/or the retainingmember 55 without interference to their utility. Also when one or moreof the rollers are caused, for one reason or another, to rock relativeto the arbor and/or an adjoining roller, such action is per- 8 mitted bythe arcuate end surfaces 76 of the flanges 75 integral with the coremembers 57 and with the vertical surfaces 71 sliding relative to thevertical wall surfaces of the associated arbor.

In the event that the pressing elements must be bodily raised from thesurfaces of the glass sheets therebeneath, pressure from the pump 131through control valves is directed through piping 52 connected to thecylinders 50 thereby swinging the pivotally mounted arms 42 upwardly.Additionally, if it is found desirable to move the apparatus back andforward across the surfaces of the glass, the motor 36 will drive thepairs of wheels 29 and 30 to carry the frame 25 along the tracks 34.This Will operate to increase the duration and effect the rolloutpressure by which the glass sheets are embedded in the layer of plasteralthough as previously mentioned the frame 25 can be fixedly mountedwithout departure from the spirit of the invention.

It is to be understood that the form of the invention herewith shown anddescribed is to be taken as a preferred embodiment of the same, and thatvarious changes in the shape, size and arrangement of parts may beresorted to without departing from the spirit of the invention.

I claim:

1. Apparatus for embedding a glass sheet in a layer of plaster materialon a worktable, comprising a plurality of pressing rollers arranged sideby side in a row, an elongated arbor on which the rollers are mounted, acarriage, means for mounting the arbor at its opposite ends upon saidcarriage, each of said pressing rollers including a non-rotatable innerportion mounted for vertical movement upon said arbor and an outerportion rotatably carried by said inner portion, and pressure responsivemeans acting upon the non-rotatable portions of said pressing rollersfor moving them vertically relative to the arbor to vary the pressure ofsaid rollers on the glass sheet, said pressure responsive meansincluding a bellows positioned between the arbor and the verticallymovable inner portion of each pressing roller and communicating with acontrol source of pressure.

2. Apparatus as claimed in claim 1, in which said arbor is hollow andclosed at its opposite ends to provide a pressure chamber therein,certain of said bellows communicating with the interior of said arbor,and means for supplying fluid under controlled pressure to the interiorof said arbor.

3. Apparatus as claimed in claim 2, including means connecting thebellows acting between the arbor and the inner portion of the endrollers in said row to separately controlled sources of pressure wherebysaid end rollers are adapted for vertical movement independently of oneanother and independently of said certain rollers.

4. Apparatus as claimed in claim 1, in which the means for mounting thearbor includes an arm supporting each end of the arbor, means forpivotally mounting the arm at one end upon the carriage, and means forselectively applying downward pressure to the opposite end of said arm.

5. Apparatus as claimed in claim 4, in which the lastnamed meanscomprises hydraulic means for urging the arm downwardly, and includingmeans carried by the carriage for limiting the downward movement of saidarms.

6. Apparatus as claimed in claim 1, in which the nonrotatable innerportion of each pressing roller comprises an annular rim encircling thearbor and spaced therefrom, a web formed integral with said rim andprovided with a rectangular opening for receiving the arbortherethrough, the side walls of said opening having a sliding fit withthe adjacent side walls of the arbor and the vertical dimension of theopening being relatively greater than that of the arbor.

7. Apparatus as claimed in claim 6, in which said bellows are disposedbetween the arbor and the inner surface of the web.

8. Apparatus as claimed in claim 6, in which the pressing rollers arespaced from one another and the web is provided with oppositely disposedflanges projecting beyond the annular rim and having arcuately curvedouter edges which engage complementary curved edges on the webs ofadjacent pressing rollers to space said rollers from one another whilepermitting angular movement thereof relative to one another.

9. Apparatus as claimed in claim 8, including a flexible ring memberencircling the arbor and closing the space between two adjacent pressingrollers.

10. Apparatus as claimed in claim 9, in which the flexible ring memberis carried by the outer portions of the two adjacent pressing rollersfor rotation therewith.

11. Apparatus as claimed in claim 10, including a tensioning rollercarried by the non-rotating inner portion of each pressing roller andengaging the inner surface of :10 a flexible ring member to distort theperiphery of the said flexible ring member progressively as the pressingroller rotates to remove plaster that may collect between adjacentpressing rollers.

12. Apparatus as claimed in claim 11, in which the periphery of theflexible ring member is concave, and in which the tensioning roller ispositioned opposite said concave portion to force said concave portionoutwardly as the pressing roller rotates to remove plaster collectedbetween adjacent pressing rollers.

References Cited in the file of this patent UNITED STATES PATENTS2,013,614 Lehrling Sept. 3, 1935 2,160,033 Rosin May 30, 1939 2,960,753Robertson Nov. 22, 1960 3,050,829 Appenzeller Aug. 28, 1962

1. APPARATUS FOR EMBEDDING A GLASS SHEET IN A LAYER OF PLASTER MATERIALON A WORKTABLE, COMPRISING A PLURALITY OF PRESSING ROLLERS ARRANGED SIDEBY SIDE IN A ROW, AN ELONGATED ARBOR ON WHICH THE ROLLERS ARE MOUNTED, ACARRIAGE, MEANS FOR MOUNTING THE ARBOR AT ITS OPPOSITE ENDS UPON SAIDCARRIAGE, EACH OF SAID PRESSING ROLLERS INCLUDING A NON-ROTATABLE INNERPORTION MOUNTED FOR VERTICAL MOVEMENT UPON SAID ARBOR AND AN OUTERPORTION ROTATABLY CARRIED BY SAID INNER PORTION, AND PRESSURE RESPONSIVEMEANS ACTING UPON THE NON-ROTATABLE PORTIONS OF SAID PRESSING ROLLERSFOR MOVING THEM VERTICALLY RELATIVE TO THE ARBOR TO VARY THE PRESSURE OFSAID ROLLERS ON THE GLASS SHEET, SAID PRESSURE RESPONSIVE MEANSINCLUDING A BELLOWS POSITIONED BETWEEN THE ARBOR AND THE VERTICALLYMOVABLE INNER PORTION OF EACH PRESSING ROLLER AND COMMUNICATING WITH ACONTROL SOURCE OF PRESSURE.